| Aim | To determine the density of solid (denser than water) by using a spring balance and a measuring cylinder. |
| Apparatus Required | A spring balance, a measuring cylinder, a beaker with water, a metal bob (or any body that is heavier than water and does not dissolve in water), a cotton string, a stand (optional). |
| Theory | Density is a measure of the amount of mass in a given volume of a substance, and it is calculated as the mass per unit volume (D= MV). The SI unit of density is kg/m3, while the CGS unit of density is g/cm3. In the case of floating bodies, water has a density of 1 g/cm3 (CGS system) or 1000 kg/m3 (SI system). If the density of a body is greater than 1 g/cm3 or 1000 kg/m3, it will sink in water (Case a). If the density of a body is less than 1 g/cm3 or 1000 kg/m3, it will float on water (Case b). If the density of a body is equal to 1 g/cm3 or 1000 kg/m3, the body will float and submerge in water, splitting its volume equally above and below the waterline (Case c). Weight refers to the force that is exerted on an object by the Earth’s gravitational pull. This force can be calculated using the formula Force = mass x acceleration, where the acceleration is due to gravity (g). Therefore, Force = mass x g, or Weight = m x g, where m is the mass of the object. The weight of an object is equal to the force exerted on it. This force is measured in Newtons (N), which is equivalent to 1 kg m/s2. Another unit used to measure weight is the kilogram force (kgf), where 1 kgf equals 1 N. The acceleration due to gravity, denoted by g, is approximately equal to 9.8 m/s2 in the SI system. To measure weight, a spring balance is commonly used. |
| Procedure | 1 .To determine the density of a solid metal bob, start by tying it to a cotton string and attaching the string to the hook of a spring balance. Ensure that the spring balance is free of any errors, and note down the zero error as ‘x.’ 2 .Next, hold the spring balance (or tie it to a stand) in mid-air with the metal bob hanging from it. Record the weight of the bob as ‘WF.’ 3 .Now, take a measuring cylinder and pour water into it. Note down the initial volume of water as ‘V1.’ 4 .Suspend the metal bob into the measuring cylinder filled with water, making sure that it does not touch the base or sides of the cylinder. 5 5 .The water level will rise, and you should measure the increase in water level, denoted by ‘VF.’ 6 .Record all the observations in a table, and use them to calculate the density of the given solid metal bob. |